Method, device and installation for the continuous displacement processing of threads

ABSTRACT

The Apparatus for implementing the method of the invention comprises in succession, on the path of the thread ( 1 ): an air suction nozzle ( 3 ); at least one spray nozzle ( 4 ) for spraying a treatment bath; a removal chamber ( 5 ) for removing the air and excess treatment bath; and an air false-twist member ( 6 ); these four elements preferably forming a single-block assembly. In the spray nozzle ( 4 ) the treatment bath is sprayed at high pressure, e.g. of the order of 2×10 5  Pa to 6×10 5  Pa (2 bars to 6 bars) in the form of micro-droplets. After the apparatus, the installation includes finishing means ( 8 ) preferably consisting in two heater drums ( 10, 11 ) having offset axes, with the thread ( 1 ) being wound over the drums and moves over them in the form of substantially touching turns.

The present invention relates to the field of continuously treatingtextile threads, whether they be constituted by a plurality ofcontinuous filaments or by discontinuous filaments of natural,synthetic, or artificial origin.

A method of continuous treatment, in particular dyeing, is known inparticular from documents FR.2.098.428 and FR.2.122.708 in which wetthread that has passed through an impregnation chamber is caused to passthrough a zone having a flow of air traveling therealong at a pressurewhich is much lower than the pressure that existed around the threadduring the operation that caused it to be wetted. The low pressure zoneis created in the supersonic flow of air at the outlet from aconverging-diverging nozzle through which the thread passes. Animprovement of that method is described in documents FR.2.219.268 andFR.2.250.421 and consists in imparting turbulence to the flow of airwithout rotating the thread.

According to the Applicant, that action of drying the thread by air isfar from satisfactory in avoiding splashes from the treatment bath, inparticular a bath of dye, on the thread leaving the apparatus and priorto being dried. In addition, when the method is put into operation, itis not easy to thread the thread through the various impregnation anddrying members, and it is necessary to make use of hooks which are inthe form of fine wire rods.

Document FR.2.282.492 discloses a method of continuous treatmentintended mainly for treating a fiber tape by means of a false-twistmember for the purpose of untwisting the tape after it has receivedinjection of a liquid, which may be a colored liquid. In that method, atthe outlet from the false-twist member, the fiber tape is surrounded bya liquid sheath which, in the preferred application, enables fibers tobe bonded to the tape by adhesion.

An object of the present invention is to make it possible to treat allkinds of thread, whether constituted by fibers or continuous filaments,while avoiding uncontrolled splashing of the treatment bath, andguaranteeing that the thread is easy to put into place when starting themethod.

This object is completely achieved by the method of treating thread incontinuous displacement which, in characteristic manner, comprises thefollowing successive operations, taken in the thread displacementdirection:

a) a suction operation in which the thread is sucked through an airsuction nozzle;

b) a spraying operation in which a treatment bath is sprayed onto thethread by means of at least one spray nozzle;

c) a removal operation in which the air and the treatment bath that hasnot been taken up by the thread are removed;

d) a false-twist operation in which an air false-twist member twists thethread; and

e) optionally an operation of drying the thread; the spraying operationbeing capable of being performed either upstream or downstream from thesuction operation.

In this method, and contrary to the teaching of document FR.2.098.482,there is no complete impregnation of the thread by passing through atreatment bath. Instead said treatment bath is sprayed, with thespraying being performed preferably at high pressure to force thetreatment bath to penetrate into the core of the thread in displacement.The quantity of bath that is sprayed is adjusted as a function of thedesired take-up rate, with the air of the suction nozzle removingsurplus treatment bath. Naturally, the primary function of the airsuction nozzle is to apply traction on the thread in its displacementdirection, said traction making it possible, when the method is set intooperation, to thread the thread without it being necessary to usemechanical means. The spraying operation while the thread is beinginserted on starting the method is preferably not itself started untilafter the thread has been threaded.

Advantageously, the bath is a bath of dye and contains a resin includingpigments. In which case, it is possible to obtain a dyed thread afterthe drying operation alone and without any need for steaming orthermosetting.

Another object of the invention is to provide an apparatus speciallydesigned for implementing operations a) to d) of the above-specifiedmethod. The apparatus comprises in succession, and on the path of thethread: an air suction nozzle; at least one spray nozzle for spraying atreatment bath; a removal chamber for removing the air and the excesstreatment bath; and an air false-twist member.

Another object of the invention is to propose an installation fortreating thread continuously, the installation comprising, on the pathof the thread and in its displacement direction: first delivery means;the above-specified apparatus; second delivery means; drying,thermosetting or steaming means, and receiver means.

The drying means preferably consist in two heating drums with offsetaxes, the thread being wound over said drums and moving in the form ofsubstantially touching turns.

The present invention will be better understood on reading the followingdescription of a preferred embodiment of an installation for dyeingthread continuously, as shown in the accompanying drawings, in which:

FIG. 1 is a simplified diagram of the installation;

FIG. 2 is a section view of the apparatus comprising the suction nozzle,the spray nozzle, the removal chamber, and the false-twist member; and

FIGS. 3, 4, and 5 are section views on lines III—III, IV—IV, and V—V ofFIG. 2.

In the treatment method of the invention, the thread 1 is subjected onits continuous displacement path to a succession of operations, namely:a suction operation by an air suction nozzle 3; a spraying operation inwhich a treatment bath is sprayed by means of a spray piece 4 having atleast one nozzle; a removal operation in which the air and the excesstreatment bath are removed by means of a removal chamber 5; afalse-twisting operation by means of an air false-twist member 6; andpreferably a finishing operation in a finishing station 8 prior to beingreceived in a receiver station 9. In the example shown, the finishingstation 8 is a drying station having two heater drums 10 and 11 withoffset axes enabling substantially touching turns to be formed thattravel continuously over the peripheral surfaces of the two drums 10 and11. The receiver station 9 is a simple winder.

On the path of the thread, upstream from the suction nozzle 3 anddownstream from the false-twist member 6, it is also possible to placerespective delivery means 2, 7 each constituted by a pair of feedrollers. These delivery means make it possible to vary the instantaneoustravel speeds of the thread; if the speed of the first delivery means 2is slower than that of the second delivery means 7, then the thread 1 isput under tension or stretched; in the opposite case the thread 1 isoverfed into the assembly 12 comprising the means for suction, spraying,removal, and false-twisting. Similarly, it is possible to vary theinstantaneous speeds of the thread between the second delivery means 7and the receiver means 9.

The suction nozzle 3 is constituted by a hollow piece 13 having acentral channel 14 through which the thread 1 passes, an annular chamber15 fed with compressed air by a pipe 16, and four ducts 17 connectingthe annular chamber 15 to the central channel 14. These four ducts 17are uniformly distributed around the channel 14, extending radially tothe axis DD of said channel, and they are inclined in the threaddisplacement direction along arrow F. The compressed air coming from thepipe 16 fills the annular chamber 15 and is expelled obliquely into thecentral channel 14 via the ducts 17, thereby pushing the thread 1 in thedirection of arrow F. It should be observed that when a free thread endis presented to the inlet 14 a of the central channel 14, said end isnaturally sucked in by the suction created by the flow of air inside thechannel 14. This is what makes it easy to thread the thread through theassembly 12.

In the example shown, the structure of the spray piece 4 is similar tothat described above for the suction nozzle 3, with a hollow piece 18, acentral channel 19, an annular chamber 20, a feed pipe 21, and fourducts 22. The feed pipe 21 is not fed with compressed air but with atreatment bath under pressure which spreads out in the annular chamber20 and is expelled into the central channel 19 via the ducts 22. Thisexpulsion of liquid at high pressure via small diameter ducts causesfine droplets to be sprayed which penetrate into the core of the thread1 passing along the channel 19.

The removal chamber 5 is constituted by a hollow piece 23 having acentral channel 24 through which the thread 1 passes and alarge-diameter removal pipe 25 on the side that opens out into areceptacle (not shown) with the recovered bath optionally being filteredand recycled.

The false-twist member 6 is constituted by a hollow piece 26 with acentral channel 27, an annular chamber 28 fed by a compressed air feedpipe 29 and four ducts 30 connecting the annular chamber 28 to thecentral channel 27. The central channel 27 as shown in FIG. 2 comprisesfive successive portions. The first portion 27 a that is furthestupstream in the displacement direction of the thread along arrow F is aconverging frustoconical portion. The three following portions 27 b, 27c, and 27 d are cylindrical portions having increasing diameters, andthe fifth portion 27 e is a diverging frustoconical portion. The fourducts 30 are disposed between the annular chamber 28 and the thirdportion 27 c of the central channel 27 in such a manner that thecompressed air penetrates tangentially relative to said channel,creating turbulent motion inside said third portion 27 c.

The second portion 27 b is of a small diameter which is slightly greaterthan the diameter of the thread 1 to be treated. Under such conditions,the air which escapes from the ducts 30 is preferentially entraineddownstream, i.e. towards the portions 27 c to 27 e, thereby conferring asuction component to the false-twist member 6, further facilitatingthreading of the thread when the installation is started. The convergingfrustoconical shape of the first portion 27 a is also designed to makesuch threading easier. In addition, the small diameter of the secondportion 27 b also serves to prevent excess treatment bath coming fromthe central channel 24 of the removal chamber 5 penetrating into thefalse-twist member 6.

The embodiment described above concerning the assembly 12 does not limitthe invention. The number of ducts, their angles of inclination relativeto the axis DD, their sections, and the feed pressure for each pipe alldepend on the quantity of treatment bath to be deposited on the thread,on the viscosity of the treatment bath, on the displacement speed of thethread, . . . .

It would optionally be possible to interchange the suction nozzle 3 andthe spray piece 4. Nevertheless, it should be observed that theapparatus as described above has a significant advantage relative tothis second version, namely that the air delivered into the centralchannel 14 of the suction nozzle 3 in the direction of arrow F preventsdroplets of the treatment bath as sprayed into the central channel 19 ofthe spray piece 4 from rising in the opposite direction to thedisplacement of the thread 1. In operation, there is therefore noleakage of treatment bath escaping via the inlet 14 a of the channel 14of the suction nozzle 3.

To ensure that the air and the excess treatment bath are removed undergood conditions, it is important for the section of the removal pipe 25to be greater than or at least equal to the section of the inlet orifice14 a of the suction nozzle 3. Similarly, the section of the centralchannel 19 of the spray piece 4 must be equal to or greater than that ofthe central channel 14 of the suction nozzle 3.

In a particular embodiment, given by way of non-exhaustive illustration,the three central channels 14, 19, and 24 had the same diameter of 5 mmand the removal pipe 25 had a diameter of 8.5 mm. The ducts 17 and 22had a diameter of about 0.5 mm to 0.8 mm. The pressure of the compressedair feeding the suction nozzle 3 and the false-twist member 6 wererespectively 3×10⁵ Pa and 6×10⁵ Pa (3 bars and 6 bars). The pressurefeeding the treatment bath in the pipe 21 of the spray piece 4 was 4×10⁵Pa (4 bars) . Under those conditions, with a treatment bath having aconcentration of about 100 grams per liter (g/l) of pigmented resin ofthe acrylic type, using a 33 tex acrylic thread at speeds of severalhundreds of meters per minute, a take-up ratio was obtained of about 10%to 20% at the outlet from the assembly 12, the take-up ratio being thequantity of treatment bath taken up by the thread relative to the dryweight of the thread. In addition, the distribution of the pigmentedresin over the cross-section of the thread was found to be entirelyuniform. The following explanation can be given. The droplets areprojected onto the thread at very high speed and they penetrate into thethread to its core; this penetration is further improved by thetemporary twist caused by the false-twist member 6, which twist goesback along the thread at least as far as the removal chamber 5.

It should also be observed that passing the thread 1 through thefalse-twist member 6 also has the effect of mechanically wringing outthe thread, which explains the low take-up ratio that can be obtained bymeans of the assembly 12.

In the installation shown in FIG. 1, the thread 1 leaving the assembly12 is dried on two heater drums 10 and 11 and is then wound. The twodelivery means 2 and 7 serve to adjust the instantaneous speeds of thetraveling thread upstream and downstream of the assembly 12 and betweenthe assembly 12 and the winder 9. It is therefore possible by adjustingthe instantaneous speeds in this way to overfeed the thread 1 as itpasses through the assembly 12. This turns out to be particularlyadvantageous for the treatment of non-thermoset textured multifilamentthreads, e.g. polyester threads. This makes it possible to avoid all ofthe operations that are usually desirable if it is desired to obtain atextured thread that is particularly voluminous and bulky. According tothe Applicant, using the installation of the invention on this type ofproduct gives results that are better than hank dyeing. Using differentlocalized speeds as above turns out to be particularly advantageous formaintaining a crimp or elastic effect on a given thread.

For reasons of ease of assembly and also of interaction between thevarious elements, it is preferable for the assembly constituted by thesuction nozzle, the spray piece, the removal chamber, and thefalse-twist member to be built up as a single block.

What is claimed is:
 1. A method of treating a thread in continuousdisplacement, the method comprising the following successive steps takenin the displacement direction of the thread: a) a suction operation inwhich the thread is sucked through an air suction nozzle; b) a sprayingoperation in which a treatment bath is sprayed onto the thread by atleast one spray nozzle; c) a removal operation in which the air and thetreatment bath that has not been taken up by the thread are removed; andd) a false-twist operation in which an air false-twist member twists thethread; the spraying operation being performed either upstream ordownstream from the suction operation and performed upstream from thefalse-twist operation.
 2. The method according to claim 1, wherein inthe spraying operation, the treatment bath is sprayed at a pressure inthe range of 2×10⁵ Pa to 6×10⁵ Pa.
 3. The method according to claim 1,wherein while the thread is being inserted on staring the method, thespraying operation is not put into operation until after the thread hasbeen threaded.
 4. The method according to claim 1, wherein the treatmentbath contains a resin including pigments.
 5. The method according toclaim 1, further comprising an operation of drying the thread.
 6. Anapparatus for treating a thread in continuous displacement, theapparatus comprising in succession on the path of the thread: an airsuction nozzle adapted to apply suction to the thread; at least onespray nozzle adapted to spray a treatment bath onto the thread; aremoval chamber for removing the air and the excess treatment bath; andan air false-twist member.
 7. The apparatus according to claim 6,wherein the air suction nozzle comprises a hollow piece comprising acentral channel for passing the thread, an annular chamber fed withcompressed air by a pipe, and a plurality of ducts connecting theannular chamber to the central channel, said ducts being disposedradially about a longitudinal axis of the central channel and beinginclined in the direction of thread displacement.
 8. The apparatusaccording to claim 6, wherein the spray nozzle comprises a hollow piececomprising a central channel for passing the thread, an annular chamberfed with the treatment bath under pressure by a pipe, and a plurality ofducts connecting the annular chamber radially to the central channel. 9.The apparatus according to claim 6, wherein the removal chambercomprises a hollow piece comprising a central channel for passing thethread, the removal chamber further comprising a side removal pipe,wherein the section of the side removal pipe is greater than or equal tothe inlet section for the thread into the air suction nozzle.
 10. Theapparatus according to claim 6, wherein the air suction nozzle, thespray nozzle, the removal chamber, and the false-twist member form asingle block assembly.
 11. An installation for treating thread incontinuous displacement, the installation comprising, on the path of andin succession in a displacement direction of the thread: first deliverymeans; an air suction nozzle adapted to apply suction to the thread; atleast one spray nozzle adapted to spray a treatment bath onto thethread; a removal chamber for removing the air and the excess treatmentbath; an air false-twist member; second delivery means; finishing means;and receiver means.
 12. The installation according to claim 11, whereinthe finishing means includes two heater drums with offset axes, thethread adapted to be wound over said drums and moving in the form ofsubstantially touching turns.